Process and cross-winding device for laying a thread

ABSTRACT

A method and an apparatus for traversing a yarn, wherein a traversing yarn guide is moved by means of an electric motor. The actual position of the yarn guide is continuously determined by means of a measuring device and supplied to a control device, which performs a comparison between the actual and desired positions of the traversing yarn guide, and the control device generates a corresponding differential signal for controlling the operation of the electric motor.

BACKGROUND OF THE INVENTION

The present invention relates to a method of traversing an advancingyarn during the winding of the yarn into a yarn package.

A method of this kind and an apparatus for traversing a yarn are knownfrom EP 0 453 622 B1. In this known process, a traversing yarn guide ismounted on a belt of a belt drive. The belt drive is driven via astepping motor in such a manner that the traversing yarn guidereciprocates the yarn within a traverse stroke. In the region ofreversal, the stepping motor is supplied with a saturation current andin the remaining region with a rated current. The motions are controlledat a position within the traverse stroke by means of a sensor.

However, the known method is subject to physical and technicallimitations. From the physical viewpoint, the stepping motor representsa spring-mass system, which is liable to vibrate in the case of rapidchanges in position and to perform uncontrolled movements. During amovement of the yarn guide, the reference or zero position is passedonly twice. The accuracy of positioning outside of the zero position isundefined. At higher rotational speeds, such as, for example, aproduction speed of 1,000 m/min., this method is no longer able tooperate with the necessary accuracy.

It is therefore the object of the invention to create a method andapparatus for traversing a yarn, which permit an exact positioning ofthe yarn within the traverse stroke. A further object of the inventionis to ensure an optimal utilization of the electric motor in eachtraverse stroke.

SUMMARY OF THE INVENTION

The above and other objects and advantages of the invention are achievedby the provision of a yarn winding method and apparatus wherein the yarntraversing mechanism includes at least one yarn guide, and meansincluding an electric motor for traversing the one yarn guide along therotating winding spindle and so as to define a traverse stroke. A sensoris provided for continuously monitoring the actual position of the oneyarn guide as it moves along the traverse stroke, and control means isprovided for comparing the monitored actual position of the one yarnguide with a predetermined desired position, and generating a controlsignal in response to a difference between the monitored actual positionof the one yarn guide and the predetermined desired position so as tocontrol the operation of the electric motor. The yarn is therebyaccurately positioned along the entire traverse stroke in accordancewith a predetermined winding program.

The invention as summarized above is not suggested by EP 0 302 461. Inthe traversing apparatus of that document, a plurality of traversingyarn guides are mounted one after the other on a belt and are driven bymeans of a servomotor. This servomotor is commuted by means of aresolver, so as to be reversed according to a predetermined desiredfunction. The position of the traversing yarn guide is not detected. Theknown traversing apparatus, which is used at production speeds from 150to 170 m/min., is totally unsuited for reciprocating a yarn attraversing speeds up to 7 m/sec. due to its high mass moment of inertia.

However, the method of the present invention facilitates such a highlydynamic movement of the traversing yarn guide without difficulties. Thespecial advantage of the invention lies in that a constant adjustmentoccurs between the actual position and the desired position of thetraversing yarn guide. A measuring device coupled with the traversingapparatus offers the possibility of utilizing the full dynamics and thefull moment of the electric motor, without incurring the risk that themotor falls out of step. Primarily, this generates a high accuracy andreproducibility in the outer ranges of the movement of the traversingyarn guide, namely in the region of the reversal at the outer edge ofthe yarn package, while the yarn is being traversed.

In the event of a deviation between the actual position and the desiredposition, a differential signal is generated for controlling theelectric motor. In this instance, the setting of the electric motor isunderstood to be the relation between the movable rotor and thestationary stator of the electric motor. Thus, it is made possible tomove the traversing yarn guide in a position-controlled manner over theentire traverse stroke. As a result of the continuous adjustment betweenthe actual position of the traversing yarn guide and the desiredposition of the traversing yarn guide which is determined by theelectric motor, the electric motor is in a position to exactly apply theenergy or torque that is required for every position of the traversingyarn guide.

The special advantage of the invention lies in that the electric motoris controllable in an amplitude-controlled manner. This means, that incase of a deviation between the actual and the desired position, theelectric motor will receive by means of the differential signal acurrent that is varied in its amplitude. In particular, this allows ahigh accuracy to be realized for the positioning of the traversing yarnguide in the reversal region.

In a further, advantageous variant of the method, the differentialsignal is also used to change the rotational speed of the electricmotor. This allows to adjust the speed of the traversing yarn guide bythe frequency-controlled motor in every position within the traversestroke to a predetermined sequence, so that the laws of winding can beput into action with a high accuracy during the formation of packages.For example, random winds, precision winds, or conical packages can berealized with corresponding speed profiles and with a high accuracy. Thetraversing speed is in a range of about 800 double strokes per minute.

In this connection, it will be especially advantageous, when for eachkind of wind a respective course of the desired position of thetraversing yarn guide is predetermined within a traverse stroke forcontrolling the electric motor. The course of the desired position ofthe yarn guide predetermines the position and the speed of thetraversing yarn guide. With that, the method is suitable for carryingout stroke reductions. The stroke reductions may be varied as desired onone side or on both sides according to a predetermined time program.

To be able to wind yarn reserves as precisely as possible at thebeginning of a winding cycle, it will be advantageous, when at thebeginning of the winding cycle, an adjustment is made between theposition of the traversing yarn guide and the setting of the electricmotor with the aid of a reference position.

Especially advantageous is the variant of the method, wherein thereference position is defined by one of the ends of a tube that receivesthe package. With that, it is ensured that despite differently longtubes, the available winding length of the tube corresponds in eachinstance exactly to the traverse stroke.

The method of the present invention offers the possibility of detectingthe actual position of the traversing yarn guide by a sensor that isoptically, acoustically, or electrically coupled with a measuringdevice. In the case of an optical detection, for example, lasers areused, which detect the position of the yarn guide by way of measuringthe distance.

However, it is also possible to use ultrasound sensors for measuring theactual position of the yarn guide.

In a particularly advantageous variant of the method, wherein the yarnguide is moved by means of a belt drive, the sensor of the measuringdevice is connected to the motor shaft of the electric motor, whichdrives a drive pulley of the belt drive.

When using this variant, it is possible to detect the angle of rotationor the number of revolutions of the motor shaft, which corresponds,based on the transmission mechanism, to the respective actual positionof the yarn guide.

Especially advantageous is the variant of the method, wherein the sensoris arranged on one of the belt pulleys, and determines an angle ofrotation or the number of revolutions of the belt pulley.

Basically, the method of the present invention can be applied to anykind of drive of the traversing yarn guide. The variant of the method,wherein the traversing yarn guide is driven by means of a stepping motoris especially of advantage because of its high flexibility. Likewise,the low moments of inertia of the stepping motors make it possible toimpart a high torque, which is necessary especially in the reversalregions of the traversing yarn guide.

The method of the present invention may be carried out both with atraversing apparatus, wherein the traversing yarn guide is reciprocatedwithin a traverse stroke, and with a traversing apparatus, wherein twooppositely driven traversing yarn guides are moved within a traversingstroke. The traversing apparatus of the present invention distinguishesitself in particular by a reproducibility of the yarn deposit on thepackage as well as by its high flexibility with respect to the packagebuild.

A particularly advantageous further development of the traversingapparatus provides that a plurality of traversing yarn guides areprovided for reciprocating a plurality of yarns in winding positionsarranged parallel to one another. In this arrangement, the traversingyarn guides moving in the same direction are driven by an electricmotor. However, for controlling the position and speed of the traversingyarn guides, the measuring device is associated to only one of thetraversing yarn guides moving in the same direction. This configurationallows to control any desired number of parallel arranged windingpositions of a machine.

To attain a high accuracy in the detection of the actual position of thetraversing yarn guide, it is preferred to use the traversing apparatus,wherein a sensor of the measuring device is in contact with thetraversing yarn guide.

With a use of a noncontacting sensor in a particularly preferred variantof the embodiment, the existing flexibility of the traversing apparatusis likewise further increased.

Thus, for purposes of determining the actual position of the traversingyarn guide, it is possible to use conventional sensors, such as opticallaser sensors, acoustical ultrasound sensors, noncontacting magnetic orcapacitive sensors, as well as electric rotation pickups.

Since due to constructional conditions the scanning of the traversingyarn guide is often confronted with difficulties, a traversing apparatusis especially advantageous, wherein the measuring device for detectingthe actual position of the traversing yarn guide is coupled with one ofthe drive means that moves the traversing yarn guide.

In this connection, the traversing apparatus wherein the traversing yarnguide is guided by means of a belt drive, represents a variant, whereinthe masses being moved are small, so that the electric motor is able toimpart the torque necessary for the high speeds.

In this variant, the belt is guided over a belt pulley and drive pulley.The electric motor is coupled with the drive pulley, so that therotation is transmitted to the belt. The belt may also be formed by acable or another tapelike means.

The further development of the traversing apparatus, wherein the sensorof the measuring device covers a number of markings provided per lengthunit on the belt, has the advantage that it thus senses the directtransmitting member of the movement of the traversing yarn guide. Inthis instance, it is possible to use as markings, for example, theprojections of a cog belt.

The embodiment of the traversing apparatus, wherein the sensor of themeasuring device is arranged directly on the electric motor in such amanner as to detect the angular position of the number of revolutions ofthe motor shaft connected to the drive pulley, leads to a particularlycompact design.

In addition, it is possible to configure the connection of the measuringdevice to the control device in such a manner that high transmissionaccuracies of the signals are attained. The adjustment between theactual position and the desired position of the traversing yarn guidecan thus be balanced within very short regulating times, whileminimizing disturbance influences.

In this connection, the drive of the traversing yarn guide by means of astepping motor is especially advantageous. As a result of the largenumber of paired poles, for example, fifty poles, it is possible toadjust the desired position of the traversing yarn guide very accuratelywithin the traverse stroke. The measuring device and the therewithconnected control system permit elimination of vibrations as occurfrequently with the stepping motor in quick reversal actions. As aresult, the stepping motor can be utilized far better than is possiblein mostly only controlled operations.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is described in more detail withreference to some embodiments illustrated in the attached drawings, inwhich:

FIGS. 1-3 are each a schematic view of a first embodiment of atraversing apparatus in accordance with the invention, each having adifferent measuring device;

FIG. 4 is a diagram with a plurality of curves of the desired positionof the traversing yarn guide within a traverse stroke;

FIG. 5 is a schematic view of a further embodiment of a traversingapparatus in accordance with the invention;

FIG. 6 is a schematic view of a further embodiment of a traversingapparatus in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 3 each show a traversing apparatus of the present invention.The traversing apparatus differ from one another by the design of themeasuring device. For this reason, the following description is commonto the traversing apparatus of FIGS. 1 to 3.

A traversing yarn guide 3 is reciprocated within a traverse stroke bymeans of an electric motor 7, for example a stepping motor.

The motion of the electric motor 7 is transmitted to the traversing yarnguide 3 via a belt 6. The belt 6 loops about belt pulleys 4.1 and 4.2 aswell as a drive pulley 5. The traversing yarn guide 3 is fixedly mountedon the endless belt 6 and reciprocated on the belt 6 between beltpulleys 4.1 and 4.2. The belt pulleys 4.1 and 4.2 are each mounted forfree rotation about an axle. The drive pulley 5 is mounted or a motorshaft 9. The motor shaft 9 is driven by the electric motor 7 inalternating directions of rotation.

Arranged parallel to the belt 6 extending between belt pulleys 4.1 and4.2 is a winding spindle 14 which mounts a winding tube 15. On the tube15, a yarn package 1 is wound. A drive roll 2 lies against the surfaceof package 1 which is formed on the tube. The winding spindle 14 isdriven via the drive roll being in circumferential contact with thepackage 1. A yarn 13 which is wound on package 1 is reciprocated bytraversing yarn guide 3 according to a preselected law of winding withinthe traverse stroke.

In this process, the position of the traversing yarn guide may assumeany desired values within the traverse stroke. The positions of thetraversing yarn guide within the traverse stroke are determined by theelectric motor 7. The diameter of the drive pulley is determined by thetorque of the electric motor 7 and the traverse stroke of traversingyarn guide 3. The circumference of the drive pulley 5 may be smaller orlarger than the traverse stroke of the yarn guide. The drive pulley 5 ismade of a light material, for example, plastic, so as to realize a lowmass moment of inertia.

The electric motor 7 is controllable via a control device 11. Thecontrol device 11 receives from a primary controller the sequences ofdesired positions within the traverse stroke. In this connection, it ispossible to input, with respect to every law of winding, the desiredvalues that are characteristic of the traversing yarn guide in itsposition and speed. Moreover, it is possible to input values forbreaking ribbons during the winding, as well as for shortening thetraverse stroke. To this end, the control device 11 receives rotationalspeed signals of package 1 and drive roll 2.

The control device 11 is connected to a measuring device 8. Themeasuring device 8 comprises a sensor 10, which detects the actualposition of traversing yarn guide 3. The position of traversing yarnguide 3 is measured by the sensor both within the traverse stroke andeven outside thereof, for example, during a yarn change. The measuringdevice 8 transmits the measuring signals to the control device 11.

In FIG. 1, the measuring device 8 is connected to an electric sensor 10which is in contact with traversing yarn guide 3.

In this embodiment, the sensor 10 consists of a potentiometer, on whichthe traversing yarn guide is reciprocated, and thus generates anelectric signal, which is received by the linear distance measuringdevice 8 and supplied to the control device 11. To detect the positionof the traversing yarn guide in a noncontacting manner, the sensor 10may be magnetically coupled with the traversing yarn guide 3.

FIG. 2 shows a measuring device which comprises an optical sensor 10.The optical sensor 10 generates a laser beam that is directed toward thetraversing yarn guide. The measuring signal is again supplied from themeasuring device 8 to the control device 11. In this process, thedistance measured by the optical sensor can be transferred within thelinear distance measuring device 8 to a position of the traversing yarnguide.

FIG. 2 shows another variant of the embodiment in dashed lines. In thisvariant, the measuring device with the optical sensor 10 is arranged insuch a manner that the belt 6 is sensed by optical sensor 10. It wouldlikewise be possible to arrange the sensor within the belt drive, so asto use as signals the projections formed in the belt in the case of acog belt.

FIG. 3 illustrates a further embodiment, wherein the measuring device isarranged directly on the electric motor 7. In this embodiment, thesensor 10 of the measuring device 8 is designed as a rotation pickup,and it detects the angular position or rotation of motor shaft 9.

However, it is also possible to arrange the rotation pickup with thelinear distance measuring device on one of the belt pulleys 4.1 or 4.2,as shown by dashed lines in FIG. 3.

All measuring devices shown in FIGS. 1-3 detect the actual position ofthe traversing yarn guide during the winding cycle. The actual positionis supplied to the control device 11, which performs a comparisonbetween predetermined desired values and actual values of the positionof the traversing yarn guide. A differential signal generated by thecontrol device 11 is supplied to the electric motor 7 for controllingsame. For example, the coils of the electric motor 7 may be switched insuch a manner that the position and speed are varied. The control device11 includes a microprocessor control and a power component for theelectric motor. By means of this power component, it is possible tocover the motor current and to change the torque of the electric motor7. Thus, both the angular position and the rotational speed of the motorshaft are controlled. The traversing apparatus requires no specialalignment of the shaft of motor 7 with respect to the traversing yarnguide 3. To determine the position of the traversing yarn guide, thecontrol device 11 may perform a reference run prior to the start of thewinding operation, so that the electric motor 7 is operated with a verylow torque in one direction to one of belt pulleys 4.1 or 4.2. The lowtorque will cause no mechanical damage.

During the winding operation, the control device 11 may monitor the beltfor breakage, in that the motor current is monitored for variation. Thebelt 6 may also be monitored for breakage by a local control unit duringthe reference run by supervising the timing.

Basically, the rotation of electric motor 7 may also be transmitted byother beltlike means, such as, for example, cables, tapes, chains, orwires.

FIG. 4 illustrates by way of example a diagram showing the curve of thedesired position of the traversing yarn guide. Plotted on the ordinateis the distance covered by the traveling yarn guide. The traverse strokeH is formed by partial lengths B_(L), L and B_(R). In the case of atraversed yarn guide, same is decelerated at each stroke end from itsguiding speed and again accelerated. The diagram shows a basic relationbetween the speed of the traversing yarn guide and the traverse stroke.The reversal of the lengths at the ends of the traverse stroke areindicated at B_(L) and B_(R). The speed of the traversing yarn guide isplotted on the abscissa. Starting at the origin of the diagram, the yarnguide is first accelerated. This acceleration occurs in accordance witha function, which may be of any desired shape, for example, circular,parabolic, hyperbolic, etc. The acceleration phase of the traversingyarn guide is completed, after a predetermined guiding speed is reached.This point is indicated by the transition from the reversal length B tothe linear length L. Within the linear length, the speed of the yarn isconstant. To reverse the movement of the yarn guide at the opposite end,the yarn guide is decelerated within the reversal length B_(R). Thedeceleration of the yarn guide occurs again in accordance with afunction. Once the yarn guide has a zero speed, the entire sequence isrepeated.

FIG. 4 shows three curves with different guiding speeds. To identify theguiding speed, the double stroke rates per minute of the traversing yarnguide are indicated. These double stroke rates are values of 300, 600,800 double strokes per minute which are commonly adjusted in practice.As a result of these curves, the desired position of the yarn guide asregards its location and speed is predetermined, and it is used forcontrolling the electric motor. In a comparison between actual anddesired values, the respectively determined actual position as regardslocation and speed is compared with the desired position. A differentialsignal generated by the control device will result in a correspondingcontrol of the electric motor.

FIG. 5 illustrates a further embodiment of a traversing apparatus inaccordance with the invention. In this Figure, identical functionalcomponents are shown by like reference numerals.

The traversing apparatus comprises two belt drives with crossing belts6.1 and 6.2. A first belt drive is formed by a drive pulley 5.1 and beltpulleys 4.1 and 4.2, which guide an endless belt 6.1. The drive pulley5.1 is mounted on one end of a motor shaft 9.1, and it is driven by anelectric motor 7.1 in counterclockwise direction (direction of arrow).The belt 6.1 mounts a yarn guide 3.1.

The second belt drive comprises a drive pulley 5.2 and belt pulleys 4.3and 4.4, as well an endless belt 6.2 that is guided therein. The drivepulley 5.2 is mounted on a motor shaft 9.2 and driven by means of anelectric motor 7.2 in clockwise direction (direction of arrow). The belt6.2 mounts a yarn guide 3.2. The belt drives are arranged in planesparallel to each other, so that the belt pulleys 4.1 and 4.3 as well asbelt pulleys 4.2 and 4.4 are coaxial with one another. A package 1 beingwound is arranged parallel to the belt pulleys below the belt drives.The package 1 is wound on a tube 15, which is driven via a windingspindle 14. The winding spindle 14 may be driven, for example, by anelectric motor. Between the belt drive and package 1, a contact roll isarranged, which is not shown in FIG. 5 for the sake of clarity.

The contact roll lies against the package surface under a contact force.The contact roll that is driven by the package 1 is operated at aconstant rotational speed during a winding cycle. To this end, the driveof the winding spindle 14 is slowed down in accordance with the increasein diameter.

A yarn 13 which advances substantially perpendicularly into the plane ofthe drawing is guided by means of yarn guides 3.1 and 3.2 along thetraverse length, which is substantially identical with the packagelength. In the position shown in FIG. 5, the yarn 13 is currently beingguided by traversing yarn guide 3.2 toward the left end of the packageby means of belt 6.2. In comparison with coaxial belt pulley 4.2 of thesecond belt drive, the belt pulley 4.4 has a smaller diameter. As aresult, the traversing yarn guide 3.2 moves in part below the traversingyarn guide 3.1 and, thus releases the yarn from its guide notch. Afterthe yarn is received by yarn guide 3.1 at the end of the traverselength, the yarn is guided in the opposite direction to the right end ofthe package 14. Since the belt pulley 4.1 of belt 6.1 has a smallerdiameter than the belt pulley 4.3 of belt 6.2, the belts 6.1 and 6.2cross each. Thus, the yarn transfer is repeated at the right end of thepackage in the same manner as the yarn transfer at the left end of thepackage. While the yarn is being guided by traversing yarn guide 3.2,the actual position of the traversing yarn guide 3.2 is measured via ameasuring device 8.2 arranged on electric motor 7.2. The measuringdevice 8.2 is identical with that shown in FIG. 3. In this respect, thedescription of FIG. 3 is herewith incorporated by reference. Themeasuring device 8.2 is connected to a control device 11.2, whichcontrols the electric motor 7.2. The electric motor 7.2 is controlled insuch a manner that the yarn guide 3.2 is moved at a guiding speed, whileguiding the yarn. After the yarn is transferred to the yarn guide 3.1 atthe end of the traverse length, the yarn guide 3.2 is moved by theelectric motor 7.2 at a change speed, which is higher than the guidingspeed. When determining the actual position of the traversing yarnguide, it is thus possible to determine any position of the yarn guidebased on the control speed of the motor and the number of revolutions.

Likewise arranged on the electric motor 7.1 is a measuring device 8.1,which is connected to a control device 11.1 associated to the electricmotor 7.1. The electric motor 7.1 is controlled in a manner analogous tothe control of electric motor 7.2. The control devices 11.1 and 11.2 areinterconnected via a central controller. As a result of thisinterconnection, it is possible to control both the guiding speed andthe change speed of the two belt drives such that the yarn istransferred in a predetermined point at the stroke end. In thisconnection, the control of the traverse drives that is made possible bythe linear distance measuring devices ensures an exact observance of thetransfer points during the yarn transfer in the stroke ends.

A further, possible arrangement is shown by dashed lines in FIG. 5. Inthis arrangement, the electric motors 7.1 and 7.2 are directlycontrolled by a central controlling device 11, which is connected to acontrol measurement device 8.2 that determines the actual position ofthe traversing yarn guide 3.1, and to a linear distance measuring device8.1 that determines the actual position of traversing yarn guide 3.2. Inthis arrangement, the traversing yarn guides are covered in theirposition only within the traverse length. Outside of the traverselength, while the traversing yarn guides are being operated at thechange speed, it is not contemplated to cover their positions. Thus, theelectric motors 7.1 and 7.2 are controlled only during the phase, inwhich the motor is driven at the guiding speed.

The traversing apparatus of the present invention is not limited to onlyone winding position, but may be extended to as many juxtaposed windingpositions as desired. For example, as illustrated in FIG. 6, two windingspindles 14.1 and 14.2 may be coaxially arranged to support two windingtubes 15.1 and 15.2. The tubes are driven by the drive rolls 2.1 and 2.2and form the yarns 13.1 and 13.2 into packages 1.1 and 1.2 respectively.Two traversing yarn guides 3.1 and 3.2, arranged one after the other,are mounted on a common belt 6 which is driven by an electric motor 7.In the illustrated embodiment, a measuring device 8 is associated withonly one traversing yarn guide 3.1.

A traversing apparatus of FIG. 5 may be extended in such a manner thatlikewise a plurality of yarn guides are mounted one after the other onone belt drive. In this instance, the belt drives could be arranged in amirror-inverted manner, so that the traversing yarn guides guided on thebelt respectively face one another.

However, the invention is not limited to traversing apparatus, whichmove a traversing yarn guide by means of a belt drive. Basically, it ispossible to control in accordance with the invention any traverse drivearrangement, wherein a yarn guide is moved and positioned by means of adrive. The constant adjustment between the actual position and thedesired position of the traversing yarn guide leads to a very highaccuracy in the yarn deposit. Thus, it is possible to reproduce thepackage buildups in each package being wound.

We claim:
 1. A method of winding an advancing yarn to form a woundpackage, comprising the steps of traversing at least one yarn guide backand forth along a rotating winding tube by means of an electric motor,while guiding the advancing yarn through the at least one traversingyarn guide and onto the rotating winding tube and so as to define atraverse stroke, continuously monitoring the actual position of the atleast one traversing yarn guide within the traverse stroke, whilecomparing the monitored actual position of the at least one traversingyarn guide with a predetermined desired position, and generating acontrol signal in response to a difference between the monitored actualposition of the at least one traversing yarn guide and the predetermineddesired position so as to control the operation of the electric motorand thereby accurately position the yarn along the entire traversestroke in accordance with a predetermined winding program.
 2. The methodas defined in claim 1 wherein the generated control signal acts tocontrol the rotational speed of the electric motor.
 3. The method asdefined in claim 1 wherein the comparing step includes comparing asequence of monitored actual positions with a sequence of the desiredpositions with respect to location and/or speed.
 4. The method asdefined in claim 3 wherein the sequence of desired positions is designedto achieve a predetermined type of wind in the resulting package.
 5. Themethod as defined in claim 1 comprising the further initial step ofadjusting the at least one traversing yarn guide to a reference positionwith respect to a setting of the electric motor.
 6. The method asdefined in claim 5 wherein the reference position is defined by one ofthe ends of the winding tube.
 7. The method as defined in claim 1wherein the step of continuously monitoring the actual position of theat least one traversing yarn guide includes optically, acoustically, orelectrically monitoring the actual position of the yarn guide by meansof a sensor.
 8. The method as defined in claim 7 wherein the step oftraversing the at least one yarn guide includes circulating a drive beltabout a drive pulley which is connected to a drive shaft of the electricmotor, and about at least one guide pulley, with the at least onetraversing yarn guide affixed to the circulating drive belt.
 9. Themethod as defined in claim 8 wherein the step of continuously monitoringthe actual position of the at least one traversing yarn guide includesmonitoring the angle of rotation or the number of rotations of at leastone of the drive pulley and the one guide pulley.
 10. The method asdefined in claim 8 wherein the drive belt includes a number of markingsarranged per unit length on the drive belt, and wherein the step ofcontinuously monitoring the actual position of the at least onetraversing yarn guide includes monitoring the markings on the drivebelt.
 11. The method as defined in claim 1 wherein the step oftraversing at least one yarn guide comprises reciprocating a single yarnguide along the traverse stroke.
 12. The method as defined in claim 1wherein the step of traversing at least one yarn guide comprisestraversing two oppositely moving yarn guides along the traverse stroke,while transferring the advancing yarn from one yarn guide to the otherat each of the ends of the traverse stroke.
 13. An apparatus for windingan advancing yarn to form a wound package, comprising a winding spindleadapted for coaxially mounting a winding tube thereupon, drive means forrotatably driving the winding tube, a yarn traversing mechanism forreciprocating an advancing yarn along the rotating winding tube to forma wound package thereon, said yarn traversing mechanism including (a) atleast one yarn guide, (b) means including an electric motor fortraversing the at least one yarn guide along the rotating windingspindle and so as to define a traverse stroke, (c) a sensor forcontinuously monitoring the actual position of the at least one yarnguide as it moves along the traverse stroke, and (d) control means forcomparing the monitored actual position of the at least one yarn guidewith a predetermined desired position, and generating a control signalin response to a difference between the monitored actual position of theat least one yarn guide and the predetermined desired position so as tocontrol the operation of the electric motor and thereby accuratelyposition the yarn along the entire traverse stroke in accordance with apredetermined winding program.
 14. The apparatus as defined in claim 13wherein the at least one yarn guide comprises a single yarn guide whichis reciprocated in opposite directions along the traverse stroke. 15.The apparatus as defined in claim 13 wherein the yarn traversingmechanism comprises a plurality of yarn guides for respectivelytraversing a plurality of yarns in parallel arranged winding positions,with the plurality of yarn guides being mounted on a common drive beltwhich is traversed by said electric motor, and wherein at least one ofthe plurality of yarn guides is associated with the sensor.
 16. Theapparatus as defined in claim 13 wherein the sensor is in contact withthe at least one yarn guide.
 17. The apparatus as defined in claim 13wherein the sensor is out of direct contact with the at least one yarnguide.
 18. The apparatus as defined in claim 13 wherein the sensor isconnected to the means for traversing the at least one yarn guide. 19.The apparatus as defined in claim 13 wherein the means for traversingthe at least one yarn guide further comprises a drive belt which isentrained about a drive pulley which is connected to a drive shaft ofthe electric motor, and about at least one guide pulley, and wherein theat least one yarn guide is affixed to the circulating drive belt. 20.The apparatus as defined in claim 13 wherein the sensor continuouslymonitors the angle of rotation or the number of rotations of at leastone of the drive pulley and the one guide pulley.
 21. The apparatus asdefined in claim 13 wherein the drive belt includes a number of markingsarranged per unit length on the drive belt, and wherein the sensorcontinuously monitors the markings on the drive belt.
 22. The apparatusas defined in claim 13 wherein the sensor is mounted on the electricmotor so as to be adapted to monitor the angular position or the numberof revolutions of the motor.
 23. The apparatus as defined in claim 13wherein the electric motor is a stepping motor.
 24. An apparatus forwinding an advancing yarn to form a wound package, comprising a windingspindle adapted for coaxially mounting a winding tube thereupon, drivemeans for rotatably driving the winding tube, a yarn traversingmechanism for reciprocating an advancing yarn along the rotating windingtube to form a wound package thereon, said yarn traversing mechanismincluding (a) first and second yarn guides, (b) means including a firstelectric motor for traversing the first yarn guide along the rotatingwinding spindle and so as to define a traverse stroke, (c) a sensor forcontinuously monitoring the actual position of the first yarn guide asit moves along the traverse stroke, (d) control means for comparing themonitored actual position of the first yarn guide with a predetermineddesired position, and generating a control signal in response to adifference between the monitored actual position of the first yarn guideand the predetermined desired position so as to control the operation ofthe first electric motor and thereby accurately position the yarn alongthe entire traverse stroke in accordance with a predetermined windingprogram, (e) means including a second electric motor for traversing thesecond yarn guide along the traverse stroke in a direction opposite thedirection of movement of the first yarn guide, (f) a second sensor forcontinuously monitoring the actual position of the second yarn guide asit moves along the traverse stroke, and (g) control means for comparingthe monitored actual position of the second yarn guide with apredetermined desired position, and generating a control signal inresponse to a difference between the monitored actual position of thesecond yarn guide and the predetermined desired position so as tocontrol the operation of the second electric motor and therebyaccurately position the yarn along the entire traverse stroke inaccordance with the predetermined winding program.
 25. The apparatus asdefined in claim 24 wherein the first and second yarn guides arepositioned and configured such that the advancing yarn is transferred ateach end of the traverse stroke from one yarn guide to the other.